John Libbey Eurotext

L'Orthodontie Française

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Le contrôle de la dimension verticale en technique de Root 2e partie : les classes II Volume 76, issue 1, Mars 2005

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Hyperdivergent, or high angle, Class II skeletal malocclusions require a reduction in that angle so that an optimal counter-reduction of the mandible can be obtained. Four of these types of cases are analyzed here to show:

- in the first, treated without extractions, the limitations of this approach: the poor esthetic result derives from the incomplete retraction of incisors because of the occlusal deficits further correction would have incurred;

- in the second, treated with extractions of upper and lower first bicuspids, that a reduction of the angles SNM from 45° to 40°, FMA from 27° to 24° and ANB from 9° to 4° was obtained;

- in the third case, treated with extractions of the upper first bicuspids and the lower second bicuspids, that a counter-rotation of the mandible was required in order not to aggravate the esthetic problem while the dental deformity was being corrected. Angle SNM was reduced from 30° to 25°, FMA from 26° to 20°, and ANB from 7° to 2°;

- and, in the fourth case, where an atypical extraction scheme was elected, that an effective orthodonticsurgical alternative is available. Thanks to an anchorage conception specifically designed for this case by T. Root4 allowing for extraction of upper first molars, angle SNM was reduced from 38° to 35°, FMA was changed from 28° to 23°, and ANB dropped from 10° to 3,5°.